Electron discharge device for high frequencies



March 22, 1949. J. s. DONAL, JR., ET AL 2,465,211

ELECTRON DISCHARGE DEVIC FOR HIGH-FREQUENCIES 2 Sheets-Sheet l FiledMarch 8, 1944 n? Cae NZM/5 Caca/H y/MQM/ March 22, 1949. 2,465,211

ELECTRON DISCHARGE DEVIC FOR HIGH-FREQUENCIES J. s. DONAL, JR., ET AL- 2Sheets-Shea?I 2 Filed March 8, 1944 pmim@ m a L s wmw Y pmu m www. n

Patented Mar. 22, 1949 ELECTRON DISCHARGE DEVICE FOR HIGH FREQUENCIESJohn S. Donal, Jr., Bai-remore B. Brown, and Car-v men Louis Cuccia,Princeton, N. J., assignors to Radio Corporation of America, acorporation of Delaware Application March 8, 1944, Serial No. 525,514

Claims.

the block adjacent the central opening and between the slots providingthe anode segments.

In another form the -cavity resonators may be bores of cylindricallyshaped chambers extending through the anode block and parallel to thecentrai opening and communicating with the central opening through slotsparallel to the axis of the central opening, the portions of the anodeblock adjacent the central opening and between the slots again providingthe anode segments.

In this type of magnetron it has been the usual practice to machine theanode block with its resonant cavities from a solid block of conductingmaterial such as copper, which may be in the form of a cylinder, spacesbeing machined at both ends of the cylinder to provide room for mountingthe -cathode and cathode leads, the ends of the cylinder being closed bycover plates soldered or otherwise sealed to the ends of the cylinder toprovide an envelope. In a variation, a separate anode has been formed bymachining or stamping, this anode being inserted into a machinedenvelope in the form of a hollow cylinder, end plates Iagain beingprovided to complete the envelope.

The machining of the envelope is time-consuming and the constructiondescribed results in dify' ficulty inmounting and centering of the cathI ode.

Usually fixed magnets or electromagnets are utilized with the magnetronsof the type described above. Because of the long air gaps made necessarybetween the electrode mount and the outside of the envelope largermagnets than desired are necessary to provide a field of desiredintensity. In any magnetron, leads must be employed to' support thecathode and make contact to the cathode and the cathode heater. Theseleads usually pass through the space at the ends of the anode and resultin an air gap in the magnetic circuit which is inconveniently large. Itis standard practice also to weld a metallic disc to the cathode leads.in order to form electrostatic shields at cathode potential at the endsof the cathode for preventing drift of the electrons out the ends of theanode cavity. This contributes to the necessity for providing largerthan desired air gaps.

In the usual form of magnetron of the type described, no way is providedto adjust the wavelength or to pre-tune the device in a simple andeffective manner. It has also' been found that due to temperaturechanges during operation, a

, variation in wavelength results.

No easy and effective way has been presented whereby a dev-ice of thekind described can be manufactured cheaply, easily and quickly on aproduction basis.

It is, therefore, an object of our invention to provide an improvedelectron discharge device of the magnetron type using cavity resonatorcircuits and particularly useful at ultra high frequencies.

Another object of our invention is to provide such a device ofsimplified design which will permit ready manufacture and eliminates theneed of extensive machining operations.

A still further object of our invention is to provide such a devicehaving a novel and effective means for supporting the cathode and itsleads and which facilitates mounting and centering of the cathode.

More particularly it is an object of our invention to provide such adevice in which the electrode mount assembly can be mounted on a headerto facilitate assembly of the mount and incorporation within anenvelope.

A further object of our invention is to provide such a device in whichthe gaps in the magnetic circuit are substantially reduced, thusdecreasing the size and strength of the magnet, electromagnet or coilsfor providing a magnetic field of required intensity.

A further object of our invention is to provide a magnetron in which theconventional and electron shields are eliminated.

A further object of our invention is to provide a simple and convenientmeans for pre-tuning .the device before sealing in the envelope.

A further object of our invention is to provide means for compensatingfor frequency shift due to temperature changes.

These and other objects will appear hereinafter.

The novel features which we believe to be characteristic of ourinvention are set forth with particularity in the appended claims, butthe invention itself will best be understood by reference to thefollowing description taken in connection with the accompanying drawingin which Figure 1 is a top view with part of the envelope removed toshow details of construction of an electron discharge device madeaccording to our invention; Figure 2 is a vertical section taken alongthe line II-II of Figure 1; Figure 3 is a vertical section taken alongthe line III-III of Figure 1; Figure 4 is a section taken along the lineIV-IV of Figure 1; Figure 5 is a top view of the magnetic insertsupporting the cathode of the electron discharge device shown in Figure1; Figure 6 is a section taken along the line VI-VI of Figure 5; Figure7 is a top view with part of the envelope removed to show a modificationof the device shown in Figure 1; Figure 8 is a vertical section takenalong the line VIII-VIII of Figure '7; Figure 9 is a side view with partof the envelope removed to show details of construction; Figure 10 is asection taken along the line X-X of Figure 9; Figure 11 is an enlargedsectional view of the cathode and its support and showing details ofconstruction; Figure 12 is a view of the strapping arrangement for theanode elements; Figure 13 is `a section taken along the line XIII inFigure 12 and Figure 14 is a section taken along the line XIV in Figure12 to show details of strapping.

In accordance with our invention and referring to Figures 1 to 4inclusive, we provide an electron discharge device of the magnetron typehaving an anode block I provided with a central opening or chamber |Ifrom which extend the radially directed slots I2 which form the cavityresonators. The end portions I3 of the block between the radial slotsand dening the central opening provide the anode segments. An indirectlyheated cathode I4 is positioned axially of the anode block. The anodeblock may be an assembly of stamped sheets of thin copper, the sheetsbeing bonded together when they have been stacked to an appropriatethickness. This eliminates the necessity for the machining operations ofthe anode block. The block may be formed ilat on the top and bottom toreduce the space necessaryfor the electrode assembly. This anode blockmay be supported from a header 22 and transversely to the header bymeans of the brackets 23 and 24.

In the usual magnetron leads must be employed to support the cathode andmake contact to the cathode and heater. In accordance with our inventionhowever, the cathode is supported from the anode block in a novelmanner. As best shown in Figures 1, 3 and 4, mounted on opposite sidesof the anode block and coaxial with the chamber is a pair of cylindricalinserts I and I6 having tapered ends and comprising magnetic materialsuch as annealed cold rolled steel. A rod and bead construction, such asI'l-IB and |'|'-|8 supports the inserts from the anode block throughwhich extend the screw members or bolts I9 and 20, the inserts beingspaced from the block by means of the spacer members, such as I9', I9"and 20', 20." These inserts may be electrically connected together bymeans of the connecting strap 2|.

In manufacture the inserts may be fastened by short rods and glass beadsto lugs |11, for example, and |81 through which the rods I9 and 20extend.Y The making of the glass bead construction I1 and I8 isperformed in a jig which holds the axis of the insert in a fixedposition with respect to the centers of the lugs and holds the faces ofthe insert at a predetermined height with respect to faces of the lug.After the beadsA are made the cathode is slipped into one of -theinserts I5 and welded. The cathode construction and support will bedescribed in greater detail below.

sembly held in place by means of the nuts associated with the bolts I8and 20. If the holes in the anode block are placed in the correctposition, the cathode is automatically centered and the insert set atthe right height above the anode. If it is desired to make a nalcentering of the cathode by hand or the use of a mandrel through theanode hole, the lugs may be made to have a loose t on the bolts and thecentering carried out before the nuts are tightened. The heater is theninserted in the cathode by a procedure to be described. The constructiondescribed above results in a very simple method of mounting. The cathodeis held in rigid position with respect to the anode and thecathode-anode space is independent of the position of the assembly onthe header or of deformation of the header.

If it is desired to hold the other end of the cathode rigidly inposition, it may be inserted in a hole I6' in the insert I6. This mightbe done if, for example, it becomes desirable to increase the heat lossfrom the free end of the cathode.

This assembly is mounted on the header 22 which consists of an ovalplate of metal ot a thickness sulcient to give suitable rigidity. Theshape need not be oval,.but any form of adequate dimensions to ilt theenvelope decided upon. In one instance the header consisted of .U25 inchstainless steel, the non-magnetic properties being of advantage in thatno disturbance of the internal magnetic circuit of the tube isoccasioned by its use. Holes are punched in the header to permit theentrance of the heater and heatercathode leads and the load line.Eyelets such as 21 and 21' are welded to the header to permit sealing-inof the heater and heater-cathode leads 26, 26' by means of the seals 28and 28', these leads in turn being connected to the conductors 25 and25' extending from the cathode and the heater. A coupling loop 29extends into the inner conductor 3U of the coaxial line includingtubular member 3| sealed to the header and having its free end sealedvacuum-tight by an insulating cup-shaped cap 32, this type of couplingline being described and claimed in a copending application of Donal andHegbar, Serial No. 496,570 tiled July 29, 1943, now U. S. Patent No.2,442,118 granted May 25, 1948, and assigned to the same Aassignee asthe present application. The junction of the tubular member 3| and theeyelets v with the header may be made vacuum-tight by welding withsilver-nickel solder at these junctions in an atmosphere ofchemicallydried hydrogen.

' The envelope 35 may be flattened as shown, resulting in an ovalopening at the bottom. This provides the ilat walls lying in a planeperpendicular to the magnetic ileld produced when the magnet is inposition. This results in a minimum air gap in the magnetic circuit whenthe envelope is used in combination with an easily constructed externalpermanent magnet with flat pole faces, such as shown at 3B and 36',registering with the inserts I5 and I6 positioned within the envelope tofurther decrease the air gap in the magnetic circuit. For the envelopedrawn cups of stainless steel may be utilized in order to avoiddisturbances of the magnetic circuit. The envelope 35 is pro- 'videdwith a lip 33 which may be sealed to the header 22 by means of atomichydrogen welding, although electric welding could also be used.

In Figures 5 and 6 are shown details of the cathode support. The insertI5 is provided with a central bore of various diameters for receivingthe cathode M, the larger bore 31 permitting the cathode flange It" tobe inserted with the cathode in contact with the insert only at therestricted portion 38 of the bore, the rest of the bore at 39 being ofvlarger diameter to provide a space between the cathode sleeve I 4 andthe insert. Thus the heat loss from the cathode may be made very small,particularly if as shown in Figure 5 spacing fingers 38' only, contactthe cathode sleeve. On the other hand under certain operating conditionsit may be necessary to increase the heat loss in which event the lengthof the restricted portion 36 of the bore may be increased to increasethe cathode area of contact.

A particularly novel feature of our invention resides in the method offorming an insert to receive the heater leads and the method ofsupporting the heater leads within the insert. Initially the insert I5may be made slightly longer than its iinal dimensions and holes drilledradially from the outside surface so as to enter the bore at the portion3l of larger diameter. The top face of the insert may then be turneddown until the top surface intersects the bores to provide open slitsIll and 6I. The leads from the heater are preformed and merely dropthrough the slits when the cathode heater I4 is placed in the cathodesleeve It. Pieces of ceramic tubing 62 and 43 may then be slipped overthe outer ends of the heater leads and pushed into the holes lill andtl, locking the heater leads in place and insulating them from theinsert. One of the heater leads 25 may be welded to the insert on itsouter surface to form a heater-cathode connection. The two heater leadsmay then be welded in any convenient manner to leads 26, 26' extendingthrough the glass seals 28v and 28.

Since the insert I5 is electrically connected to the cathode and to theinsert I6 by rods I9 and 26, the inserts are at cathode potential andact as shields and thus prevent loss of electrons from the anode space.The space between the ends of the inserts and the anode block andbetween the inserts and the walls of the envelope need be only sucientto withstand the anode-cathode diiference of potential and may be of theorder .O30 to .040 inch each. These spaces plus the thin walls of theenvelope are the only gaps in the magnetic circuit, except for the anodethickness. Thus no space is lost due to the thickness of a non-magneticcathode support. Furthermore the fact that the inserts can be varied inheight means tubes of different anode length may be conveniently fittedinto the same envelope merely by changing the height of the inserts.

As shown the inserts are tapered. The degree of taper employed may beused to concentrate the magnetic eld in the anode space in any desiredmanner.

The spaces between the anode block and the inserts are not Wasted asregards the magnetic circuit since it is known that they are necessaryin order to provide magnetic coupling between the cavity resonators ofthe tube. Actually the surfaces of the inserts nearest the anode aifectthe operation of the tube in that the wavelength of the tube is afunction of the size of these surfaces and of their distance from theanode. If the eiect upon the magnetic circuit is desirable, the area andposition of the inner faces of the inserts may be used to adjust thewavelength of. -the tube before the envelope is welded on.

It may also be desirable to utilize plates of non-magnetic materialaillxed to the inserts and make them adjustable in order that thespacing from the surface of the anode block maybe varied. This isillustrated in Figure 6 by means of the plate 83 supported in threadedengagement at 84 on the insert I5. The wavelength of the tube may beadjusted by advancing or retracting this plate, of which one may bepositioned on each of the inserts. This arrangement is quite effectivein that the movable plates cover a suflicient area of the outer ends ofthe cavity resonators to permit the desired tuning and yet not disturbthe magnetic circuit. It is also obvious that this plate could belsupported on the rods I9, 20, the plate being adjusted as to spacing bymeans of inserts.

It has been found that magnetrons change their wavelength with operatingtemperature due usually to thermal expansion of the cavity resonators.This upward change in wavelength can be automatically compensated for inour tubes by utilizing materials for inserts which have a lowercoefficient of thermal expansion than the materials used for the rods I9and 2|] and spacers I9', I9", 2n', 20". Thus the distance of the insertsfrom the anode and the capacitance of the cavities and, hence, theWavelength would be reduced as the tube warms up. This is practicalsince the wavelength is very sensitive to the distance of the insertsfrom the anode block. The use of threaded plates, such as 83, wouldincrease the compensating wavelength change as long as they affected thecapacitance only, of the cavities. If desired, these plates might bepositioned over the outer portion, only, of the cavities, and henceaffect cavity inductance rather than capacitance. If their effect thenbe made greater, due to larger area or closer spacing, than the effectof the inserts upon the capacitance, compensation for wavelengthincrease due to temperature increase would be obtained by mounting theplates on supports of such thermal expansion characteristics that theplates are moved closer to the ends of the cavities as the temperatureof the assembly increases, since it is known that closer spacing resultsin a reduction of cavity inductance and hence of wavelength.

In Figures '7 to 14, inclusive, is shown a modiiication of the deviceshown in Figure l. The anode block is provided with a central chamber 5Iinto which extend a plurality of radially positioned fiat fin-likeelements 52, the inner edges of which provide anode segments and thespaces between which provide the cavity resonators. The cathode 53 ispositioned axially of the space defined by the anode segments.

As before, a pair of magnetic inserts 5H and 55 are positioned on eitherside of the anode block. Bridging members 56 and 51, which may be ofconducting material, support the inserts. These in turn can beinsulatingly supported from the anode block by means of the bolts 5B and59 having thereon insulating spacer collar vmembers 60, 60' and 6I, 6I',for example, and the insulating collar 62 surrounding the bolts withinthe anode block. The electrode assembly is positioned vertically withinthe envelope and secured to the header 65 by means of bolts extendingthrough the blocks 63 and 64 secured to the header or extending throughthe header. The header is provided with the eyelets through which thecathode and heater leads 66 and 61 extend and to which they are sealed.The inner ends of these leads are connected by means ot conductor il toone side of the cathode heater and by 89\to the bridging member 56. Thecoupling loop extends through a passageway in the anode block into oneof the cavity resonators as shown in Figure 8 and is connected to theinner conductor 1| of the coaxial line, the outer tubular member 12 ofwhich is sealed to the header, the end being sealed oit vacuum-tight bymeans of the insulating cup-shaped member 13. In order to increase theheat dissipation from the device there are provided a plurality ofradiating tins 14 which are secured to the header as shown or to theblocks 63 and 64 if these extend through the header. Il the blocks 63and 64 are not extended through the header, screws orl bolts 63' and 64'may be threaded into the -blocks 63 or 64 through the header so thatthere is direct heat conduction from the anode block to the radiatingiins 14.

An external magnet having pole pieces 16 and 16' is mounted externallyof the envelope 15 and provides the magnetic circuit with the inserts 64and 55.

In the present arrangement the cathode 53 is supported by means of theinsert 54 having at its outer end a groove 11, one end 1B of the heaterbeing welded to the insert and the other extending externally of theinsert at 19. The heater is coated with insulating material. A cover 11'is positioned over the groove. While insert 54 is shown as in contactwith the cathode sleeve through the length f the bore to increase heatdissipation from the cathode. the bore could be enlarged a shown at 39in Figure 6.

In Figures 12 to 14, inclusive, is vshown the method of strappingalternate anode segments together. As shown in Figure 13, which is ascction taken along the line XIII of Figure 12, the anode slat or'n 52is provided with a slot 52' into which t the ring-like conducting straps8| and 80, the ring 8| being electrically connected to the radial slat52. Alternate slats are provided with slots 52 through which the strapmembers 80 and 8| pass. In this case the strap 8| has no contact withthe anode slat whereas the larger diameter strap 80 contacts the anodeslat.

The purpose of the strapping is to increase the emciency of the tube andcould as well be used in the form shown in Figures 1 to 6, inclusive. Invarious mechanical forms, straps are electrical connections betweenanode segments, the choice of segments connected or left unconnectedbeing either a matter of experience in the art or a matter decided fromtheoretical consideration. t

While we have indicated the preferred embodiments of our invention ofwhich we are now aware and have also indicated only one specicapplication for whichour invention may be employed, it will be apparentthat our invention is by no means limited to the exact forms illustratedor the use indicated, but that many variations may be made in theparticular structure used and the purpose for which it is employedwithout departing from the scope of our invention as set forth in theappended claims.

What we claim as new is:

1. An electron discharge device having a support member and an electrodeassembly, said electrode assembly including an anode means mounted onsaid member and having a plurality of anode elements defining a space, acathode for supplying electrons within said space and means insulatinglysupporting said cathode with respect to said anode means and includingan element of magnetic material insulatingly mounted on said anode meansadjacent said anode elements, and a. magnet having a pole pieceregisterlng with the element of magnetic material.

2. An electron discharge'device having a support member and an electrodeassembly including an anode means mounted on said member and having aplurality of anode segments defining a space, a cathode for supplyingelectrons within said space and means insulatingly supporting saidcathode with respect to said anode means and including a rst element ofmagnetic material insulatingly mounted on one side of said anode meansadjacent said anode segments. a second element of magnetic materialinsulating- 1y mounted on the oDDOsite side of the anod means adjacentsaid anode segments and registering with said rst element, and a magnethaving its pole pieces registering with the elements of magneticmaterial.

3. An electron discharge device having a support member and an electrodeassembly including an anode block mounted on said member and having aplurality of anode elements dening a space, a cathode for supplyingelectrons within said space and means supporting said cathode andcomprising a member of magnetic material insulatingly mounted on saidanode block and having a bore, a portion of said cathode beingpositioned within said bore.

4. An electron discharge device including a header member, an electrodeassembly including an anode mounted on said header member, said anodehaving a plurality of anode elements defining a space, a cathode forsupplying electrons within said space and means supporting said cathodeand including a member of magnetic material insulatingly mounted on saidanode ado jacent said anode elements, and an envelope 'sealed to saidheader member and positioned close to said member of magnetic material,and external means providing a magnetic circuit through said member ofmagnetic material.

5. An electron discharge device including a at header member, anelectrode assembly mounted on said header member and including a iiatanode block mounted normal to said header member, said block having aplurality of anode elements defining a space, a cathode for supplyingelectrons within said space and means supporting said cathode andincluding a rst member of magnetic material positioned on one side ofsaid anode block adjacent said anode elements, and a, second member ofmagnetic material positioned on the other side of said anode blockadjacent said anode elements and registering with the rst member ofmagnetic material, and an envelope sealed to said header member andpositioned closely adjacent said members of magnetic material, andexternal means providing a magnetic circuit through said members ofmagnetic material.

6. An electron discharge device having an electrode assembly includingan anode block having a plurality of anode elements defining a space. acathode for supplying electrons within said space and means supportingthe cathode from said anode block and comprising a first member ofmagnetic material having a bore extending therethrough, said cathodebeing positioned within said bore and means insulatingly supporting saidmember of magnetic material from one side of said block, and a secondmember of magnetic material insulatingly supported on the opposite sideof said anode block and registering with said rst member, and meansadjacent said members of magnetic material for producing a magneticiield within said central space surrounded by said anode elements.

7. An electron discharge device having an electrode assembly includingaflat anode block having a plurality of anode segments and cavityresonators connected between said segments, a cathode positioned axiallyof said anode segments and means supporting the cathode from said anodeblock and comprising a first member of magnetic material having a boreextending therethrough, said cathode being positioned within said boreand means insulatingly supporting said member of magnetic material fromsaid block, and a second member oi magnetic material on the other sideof said anode block and registering with said iirst member, and meansadjacent said members of magnetic material for producing a magnetic ieldbetween said cathode and said anode elements.

8. An electron discharge device having an electrode assemblyincluding-an anode block, said block having a plurality of anodeelements deiining a space, and a cathode for supplying electrons withinsaid space, members of magnetic material positioned on opposite sides ofsaid anode block and registering with the central space in said block,and means insulatingly supporting said members of magnetic material fromsaid block, one of said members of magnetic material supporting saidcathode, an envelope including a header, said header comprising a hatconducting member, said electrode assembly being supported from saidheader, said header having a plurality of apertures, tubular membersextending outwardly from said apertures and leads extending through saidapertures and insulatingly sealed through said tubular members, saidleads being connected to said cathode.

9. An electron discharge device having an electrode mount assemblyincluding an anode block, said block having a plurality of anodeelements dening a space, and a cathode for supplying electrons withinsaid space, members oi magnetic.

material positioned on opposite sides of `said anode block andregistering with the central space in said block, and means insulatinglysupporting said members of magnetic material from said block, one ofsaid members of magnetic material having a bore extending therethroughand into which said cathode extends and is supported thereby, anenvelope including a header, said header cornprising a flat conductingmember, said electrode mount assembly being supported from said header,said header having an aperture, a tubular member extending outwardlyfrom said aperture, and a coupling loop terminating at said anode blockadjacent said anode elements and extending through said tubular member,and providing with said tubular member a coaxial line.

l0. An electron discharge device having an electrode assembly includingan anode block of fiat elongated construction, said block having aplurality of anode elements dening a space, and a cathode for supplyingelectrons within said space, members of magnetic material positioned onopposite sides of said anode block and registering with the centralspace in said block, and means insulatingly supporting said members ofmagnetic material from said block, one of said members of magneticmaterial supporting said cathode, a header comprising a iiat conductingmember, said electrode mount assembly being supported from said header,and a iiattened envelope sealed to said header member and having ilatwalls closely adjacent said members of magnetic material, and anexternalmagnetic means closely adjacent the walls of said envelope andregistering with the members of magnetic material for providing amagnetic circuit.

l1. An electron discharge device having an electrode assembly includingan anode block of iiat elongated construction, said block having aplurality of anode segments defining a space, and cavity resonatorsconnected between said anode segments, and a cathode positionedcoaxially of said space, a plurality of members of magnetic materialpositioned on opposite sides of said anode block and registering withthe central space in said block, and means insulatingly supporting saidmembers of magnetic material from said block, one of said members ofmagnetic material having a bore extending therethrough and into whichsaid cathode extends and is supported thereby, a header comprising afiat conducting member, said electrode assembly being supported fromsaid header, said header being provided with a plurality of apertures,tubular members extending outwardly from said apertures and leadsextending ,through some of said apertures and insulatingly sealedthrough said tubular members, and connected to said cathode, and acoupling loop terminating at said anode block and extending throughanother of the tubular members extending from said header member andproviding therewith a coaxial line, and a attened envelope sealed tosaid header member and having flat Walls closely adjacent said membersof magnetic material, and an external means closely adjacent the wall ofsaid envelope and registering with the members oi magnetic material forproviding with said members of magnetic material a magnetic circuit.

12. An electron discharge device including an anode, a cathode, and amember of magnetic material supported adjacent said anode and having acentral bore extending therethrough, the bore being enlarged at one endfor a comparatively short distance for providing a recess, the borebeing enlarged at its other end for a comparatively longer distance, anda cathode sleeve having a ange tting within the recess at said one endand extending through the bore and in contact with the bore between saidrecesses, said member of magnetic material having radially directedpassageways extending therethrough and communicating with said recess atsaid one end of said bore, and a cathode heater Within said cathodesleeve and having heater leads extending from said heater through saidpassageways, and insulating tubular members surrounding said heaterleads within said passageways, the portion of said bore in contact withsaid cathode sleeve being in contact with said sleeve at spaced pointsaround the circumference of said cathode sleeve to reduce heatconduction from said cathode.

13. An electron discharge device including an anode, a cathode and amember of magnetic material supported adjacent said anode and having acentral bore extending therethrough, said bore being enlarged at one endfor a comparatively short distance and providing a recess, and a cathodesleeve having a flange fitting within the recess and extending throughsaid bore, said member of magnetic material having radially directedpassageways extending therethrough and communicating with the recess,and a cathode heater within said cathode sleeve and having Y 11 heaterleads extending from said cathode heater through said passageways.

14. An electron discharge device including an anode, a cathode and amember of magnetic material supported adjacent said anode and having acentral bore extending therethrough, the bore being enlarged at one endfor a comparatively short distance and providing a recess, and a cathodesleeve having a iiange fitting within the recess and extending throughsaid bore and in contact with said bore for only a part oi the length ofsaid bore, said member of magnetic material having radially directedpassageways extending therethrough and communicating with the recess,and a cathode heater within said cathode sleeve and having heater leadsextending from said cathode through said passageways, and insulatingtubular members surrounding lsaid heater leads within said passageways.

15. An electron discharge device having an electrode assembly includingan anode having a plurality of cavity resonators and having a pluralityof anode segments defining a central space, said cavity resonators beingbetween said segments, a cathode for supplying electrons within saidspace, a conducting member mounted on said anode adjacent saidresonators and supporting said cathode, and a conducting plate mountedon said member adjacentsaid cavity resonators and adjustable toward andfrom said cavity resonators for pre-tuning said electron dischargedevice.

16. An electron discharge device having an electrode assembly includingan anode having a plurality of cavity resonators and having a pluralityof anode segments defining a space, said cavity resonators being betweensaid segments, a cathode for supplying electrons within said space andmeans supporting the cathode adjacent said anode and including aconducting member n mounted on said a'node, and a conducting platethreaded on said member adjacent said cavity resonators, whereby saidplate is adjustable toward and from said cavity resonators for pretuningsaid electron discharge device.

17. An electron discharge device having an electrode assembly includingan anode having a plurality of cavity resonators and having a pluralityof anode segments defining a space, said cavity resonators being betweensaid'segments, a cathode for supplying electrons within said space andmeans supporting the cathode adjacent said anode block and comprising amember of magnetic material adjacent and registering with said centralspace, and a non-magnetic conducting plate mounted adjacent said cavityresonators and supported on said member of magnetic material andadjustable toward and from said cavity resonators for pre-tuning saidelectron discharge device. l

18. An electron discharge device including an envelope having anenvelope including a header member of conducting material, an electrodeassembly mounted on said header member and including an anode block,said block having a plurality of anode elements defining a space and acathode for supplying electrons within said space.

12 said snode being supported from said header member by conductingmembers iixed to said anode and to said header member and extendingthrough said header member, and a plurality o! heat radiating unsmounted externally of said header member on said conducting memberssupporting said anode.

19. An electron discharge device including an envelope having anenvelope including a nat header member of conducting material, anelectrode assecmbly mounted on said header member and including anelongated anode block, said block having a plurality of anode elementsdeiining a space and a cathode for supplying electrons within saidspace, said anode being supported from said header member by conductingmembers fixed to said anode at opposite ends thereof and to said headermember, a plurality of heat radiating ns mounted externally of saidheader member, and heat conducting means extending through said headermember and supporting said iins in heat conducting relationship on saidconducting members supporting said anode.

20. An electron discharge device having an electrode assembly includingan anode having a plurality of cavity resonators and having a pluralityof anode segments defining a space, said cavity resonators being betweensaid segments, a cathode for supplying electrons within said space, andmeans supporting the cathode adjacent said anode and including a memberof magnetic material. said member of magnetic material beinginsulatingly supported on said anode and positioned adjacent said anodesegments, whereby changes in the distance of said member from saidsegments vary the capacitance of the resonant cavities, said member ofmagnetic material and said means insulatingly supporting said member ofmagnetic material on said anode having different coeiiicients of thermalexpansion to compensate for changes in resonant wavelength due tothermal expansion of said resonators.

JOHN S. DONAL, JR.

BARREMORE B. BROWN. A CARMEN LOUIS CUCCIA.

REFERENCES CITED The following references are of record in the 5 ille ofthis patent:

UNITED STATES PATENTS Number Name Date 2,187,149 Fritz Jan. 16, 19402,238,272 Linder Apr. 15. 1941 2,404 212 Bondley July 16, 1946 2,406,277Bondley Aug. 20, 1946 2,408,235 Spencer Sept. 24, 1946 2,408,236 SpencerSept. 24, 1946 2,408,238 Spencer Sept. 24, 1946 2,408,903 Biggs et alOct. 8, 1946 2,412,824 McArthur Dec. 17, 1946 FOREIGN PATENTS NumberCountry Date 449,920 Great Britain July 7, 1936 509,102 Great BritainJuly 11, 1939

